docs: def filter(self):
          """ returns the key/value pair of a geometry filter """
  
          val = {"geometryType":self.geometryType,
                  "geometry": json.dumps(self._geomObject.asDictionary),
                  "spatialRel": self.spatialRelation,
                  "inSR" : self._geomObject.spatialReference['wkid']}
          if self._buffer is not None and \
             self._units is not None:
              val['buffer'] = self._buffer
              val['units'] = self._units
          return val